Collision detection devices in moved machines, apparatuses, or robots may be integrated in a housing cover. Housing covers for collision detection are also used in medical imaging apparatuses. A medical imaging apparatus with collision detection is known from the U.S. Pat. No. 5,570,770, for example.
Medical imaging apparatuses for medical diagnosis or therapy generally have an X-ray emitter and an X-ray detector. Each of the X-ray emitter and the X-ray detector is in a housing. These two components are arranged at a distance from each other. A patient to be examined or to be treated is positioned between the X-ray emitter and the X-ray detector. The X-ray emitter and the X-ray detector are positioned relative to the body of the patient such that an image of the desired cross section of the interior of the body may be taken. The medical apparatus may in most cases be oriented and positioned with the aid of a motorized drive.
Apparatuses of this kind are often equipped with a C-arm (e.g., an arc-shaped mount that may be rotated about several planes with the aid of a rail system). During the use of the medical imaging apparatus, a moved part (e.g., the X-ray detector) comes close to the object to be examined in order to achieve the desired image quality. The X-ray detector has a comparatively large front face for receiving the X-rays, and any desired point on this front face or on the periphery may come into contact with the patient to be examined. Such a collision may occur in any direction of movement of the X-ray detector. This is undesirable, and therefore, an apparatus of this kind is equipped with a detection device for detecting the collision with an object.
If a contact between the movable part of the apparatus and the object is detected, the movement of the apparatus may be stopped in order to minimize the severity of the consequences of a collision. In the U.S. Pat. No. 5,570,770, a medical X-ray apparatus that is equipped with an electrical detection device for detecting collisions is described. Sensors in the apparatus are configured to measure the current and the power consumed by the drive motor. These parameters give an indication of the instantaneous force exerted on the movable part. This instantaneous value may be compared with an expected value for the force. If the difference between the instantaneous value and the expected value exceeds a predetermined threshold value, it is assumed that the movement of the movable part is impeded by an object and a collision is thus taking place. Accordingly, an alarm signal is generated, and the movement is stopped.
Housing covers for movable medical imaging apparatuses or parts of covers, in which a collision with an object acts on an electric switch or on electrically switchable contacts, are known. Housing covers of these kinds are, for example, mounted on springs, of which the positional shift caused by a collision is detected. There are solutions with elastic materials that, with a predeterminable resilience, activate the electric switch. The switching signals thus obtained are used to switch off a movement of the medical imaging apparatus.